Abstract:
An experiment was carried out to find suitable ratio/s of inorganic fertilizer and
compost, which could give an economic yield of onion (cv. Jaffna Local). This
experiment was conducted for two seasons at the Agronomy farm, Eastern University,
Sri Lanka. Five treatments were included according to the different ratios of inorganic
fertilizer and compost as basal application as follows. Recommended dosage of
inorganic fertilizer [Urea (100 kg ha'1), Triple Super Phosphate (100 kg ha'1) and
Muriate of Potash (50 kg ha'1)] (Tj), three-fourth the recommended inorganic fertilizer
+ compost (2 1 ha'1) (T2), half the recommended inorganic fertilizer + compost (4 1 ha'1)
(T3), one-fourth the recommended inorganic fertilizer + compost (6 t ha'1) (T4) and
compost alone (8 t ha'1) (T5). These treatments were arranged in a Randomized
Complete Block Design with four replications. Crop was managed and top dressing was
done according to the recommendations. Number of roots and number of leaves per
plant were recorded at regular intervals and number of bulbs per plant and yield were
measured at the time of harvesting. Collected data were analyzed statistically.
Results revealed that there were significant (p<0.05) differences in the number of
leaves and number of roots between different treatments during the early stage of
growth. Compost applied treatments (T5) had more bulbs per plant than inorganic
fertilizer applied treatment (Ti). High yield (5.03 t ha'1) was obtained from inorganic
fertilizer applied treatment (Ti), meanwhile compost treatment (T5) had produced
lowest yield (3.43 t ha'1). It was also observed that, there were no significant (p<0.05)
differences in the yield between Ti andT2 as well as and T3. The inorganic fertilizers
would have compensated with slow release of nutrients from the compost and their
combined effects would have increased the yield. From this study it could be stated
that, half the recommended inorganic fertilizer and compost at the rate of 4 t ha'1 (T3)
produced the economic yield (4.75 t ha'1) of Onion.
